1. Do a clean checkout, which creates all the files with the current
date-time. The lex files now have essentially the same timestamp and CVS
sets them to the time when it writes the files.

2. Run tests, i.e. bjam, which see the equal timestamps and rebuilds
those files because they are not newer than the dependencies.

3. Do an update, when doing the next test iteration, and one sees the
"M" files.

My current solution was to delete the two lex files, and on the next
update CVS gives them a timestamp later than the rest of the files. The
real solution would be for the version control software to set the
timestamps to the one in the repo. But AFAICT neither CVS, nor SVN, have
such an option. Another possible solution is to change bjam to treat
equal timestamps as up to date in the dependency analysis.